You're right, as you said, this isn't a surprising result. Chelsea are indeed quite strong this season, despite their failure to secure full points in the opening week. However, we also need to look at the broader strength of a team.
The real test for Chelsea will come when they face Liverpool, Arsenal, or Manchester City. If Chelsea can match them or even beat them, I think Chelsea deserves to be the favorite to win the title this season. Maresca has been slowly turning Chelsea around after a poor run of form.
It seems that the international club competitions have also brought them closer together. Chelsea can play as a team, though West Ham isn't a great team overall, but scoring five goals can boost Chelsea's confidence. Their mental strength will also improve. Assessing too early is quite difficult because the league is a competition with many matches. Consistency in performance is the key to a team's success.